1. Field of the Invention
The present invention relates to a hard disk drive, and more particularly, to a disk spacer having a mass eccentricity used for disk balancing, a hard disk drive having the disk spacer, and a disk balancing method using the disk spacer.
2. Description of Related Art
Hard disk drives are one known type of auxiliary memory device for a computer. Hard disk drives reproduce information stored on a magnetic disk using a magnetic head and record information on the magnetic disk.
FIG. 1 is a cross-sectional view of a conventional hard disk drive. Referring to FIG. 1, a hard disk drive 10 includes a base member 11, a spindle motor 20 installed on the base member 11, first and second disks 22 and 26 which are data recording media inserted around the spindle motor 20 and rotating, and a disk spacer 30 having a ring shape and interposed between the first and second disks 22 and 26 to separate the first disk 22 from the second disk 26 by a predetermined distance.
The disks 22 and 26 are rotated by the spindle motor 20 at a high speed during the operation of the hard disk drive. However, the rotational center 21 of the spindle motor 20, the rotational center 23 of the first disk 22, and the rotational center 27 of the second disk 26 do not accurately match due to allowance existing in the first and second disks 22 and 26 themselves and allowance occurring during an assembly process. When the eccentricity of the first and second disks 22 and 26 is severe, vibration and noise increase during the rotation of the first and second disks 22 and 26 and a positional error signal (PES) property is deteriorated. When the eccentricity increases further, collision between a magnetic head and the disks may occurs.
One way to decrease a degree of the eccentricity of the disks 22 and 26 to reduce the vibration and noise caused due to the rotation is referred to as disk balancing. Conventionally, as shown in FIG. 1, a method of locating a mass center 23 of the first disk 22 and a mass center 27 of the second disk 26 at the opposite positions with respect to a mass center 21 of the spindle motor 20 has been used. However, the method has a problem that the actual effect of disk balancing is insufficient because a degree of the eccentricity of the disk spacer 30 is not considered. Although the degree of the eccentricity of the disk spacer 30 is negligible, if the difference in the mass eccentricity between the first and second disks 22 and 26 is severe, the actual effect of disk balancing cannot be expected.